Ambient temperature-processed aquatic animal feed and process for making same

ABSTRACT

This invention relates broadly to a novel ambient-temperature process for making aquatic animal feed including fish and crustaceans and to the aquatic animal feed so produced.

FIELD OF THE INVENTION

This invention relates broadly to a novel ambient-temperature processfor making aquatic animal feed including fish and crustaceans and to theaquatic animal feed so produced.

BACKGROUND OF THE INVENTION

There is considerable waste of fish food supplied for feeding fish inrearing tanks, ponds in fish hatcheries and fisheries and in aquaculturefields due to undesirable characteristics of commercial fish food. Earlyexperiments comparing meal to pelleted type feed demonstrated that manyfinfish utilize pelleted feed more efficiently. Many of the small mealparticles were not ingested, resulting in poorer feed conversion anddecreased water stability resulting in reduced water quality. This didand continues to create an unsuitable and unhealthy environment for thedesired aquatic organism. To minimize these undesirable effects, manycommercial feeds are processed into pellets.

However, many disadvantages exist in the pelleted feed commerciallyavailable. One major disadvantage of the commercially available feed isthe high temperatures and pressures used during conventional screw-typeextrusion mill processing. These harsh conditions destroy heat labilefeed ingredients, such as medications, vaccines, growth promoters,vitamins, minerals and other nutrients that are advantageous, albeitnecessary in many fish diets. For example, approximately 50% of vitaminC, 35% of vitamin A and 35% of thiamine are lost during commercialextrusion processing. Similar results occur for other fortifying agentsduring processing and storage. As a consequence, overfortification oflabile nutrients in processed fish feed is currently necessary.

Efforts to provide a stable aquatic animal feed have been made. Gunteret al., U.S. Pat. No. 3,889,007 (issued Jun. 10, 1975) discloses a foodcomposition for aquatic organisms and particularly crustaceanscomprising fish meal and a fish extract, fish soluble, fish oil and abinder that may be an organic binder, such as gelatin, guar gum, agar,CMC alginate ester, collagen, and pregelatinized starch, and sea water.This feed still involves standard processing techniques, having thedisadvantages of high temperatures and pressures.

Feed texture is also important for many aquatic animals. Commerciallyprocessed pelleted feed may be too hard as to be unpalatable to somefish and consequently be rejected by them. The hard pellets may also beso dense as to sink where they are not readily available to fishpreferring floating feed. Conversely, the pellets may be so soft andfriable that they disintegrate or dissolve too quickly. These feeds havethe same disadvantages of meal feed, namely, poor feed conversion anddecreased water quality due to increased growth of algae and aquaticvegetation.

Attempts have been made to increase the palatability of fish feed. Forinstance, Cox, U.S. Pat. No. 4,935,250 (issued Jun. 19, 1990) disclosesincreased palatability of fish feed pellets by coating preformed pelletswith a coating of soft and flexible consistency that may be formed ofalginate or guar gum set by calcium chloride solution or may incorporategum tragacanth, pectin or gelatin.

Lastly, fishery and aquaculture management involves many different feedformulations to ensure that various types of fish are receiving propernutrient requirements, texture and size. For instance, shrimp areparticularly difficult to nourish adequately since they require a bottom(sunken) food and are raised mostly in closed water systems. As notedabove, most finfish prefer floating type feed. With existing technology,a floating feed must contain starch in the feed mix to make it float.When the starch is subjected to high temperatures and pressures thestarch will gleutinize or stick together. Then as the pressure on thestarch is relieved, it expands trapping air in the feed. This trappedair makes the feed float. Feed produced in this way exposes the feedingredients to high temperatures (above 220° C.) and pressures (8atmospheres). These harsh conditions destroy heat labile feedingredients. Presently, farmers must either purchase pre-formulatedcommercial feed, possessing the disadvantages outlined above or musthave expensive processing equipment such as extrusion mills to formulateand produce their own feed. These are very costly limitations to thefisheries and aquaculture businesses.

The aquatic animal feed of the prior art embody one or more of thedisadvantageous characteristics of instability in water, inadequatenutritional value, causation of poor water quality, poor palatability orcostly processing. It would be of great value to the industry to providean alternative feed and process for producing said feed which is free ofthe above-mentioned disadvantages. None of the prior art compositions orprocesses provide all of the desirable characteristics of the stableaquatic animal feed of the present invention.

SUMMARY OF THE INVENTION

The present invention serves to solve the problems of water instability,labile nutrient loss, poor palatability and costly processing byproviding an ambient-temperature-process for making aquatic animal feedand the ambient-temperature-processed feed so produced, comprising (a)mixing alginate, feed ingredients and fresh water to make a slurrywherein said slurry comprises 0.5-10% alginate, and (b) at lowtemperatures, exposing said slurry to divalent cations, such as calcium,to form a water stable alginate gel, and (c) forming a water stableaquatic feed pellet. The present invention is compatible with typicalleast cost formulation practices.

Another aspect of the invention is the ambient-temperature process orfeed so produced wherein said slurry further comprises one or morefortifying agents including vitamins, minerals, pigmentation aids,proteins, amino acids (natural or synthetic), fats, oils, flavorings,medicaments, and foam stabilizers.

A further aspect of the invention is the ambient-temperature process orfeed so produced further comprising the step of whipping a controlledamount of air or nitrogen into said slurry produced by step (a) beforeexposing said slurry to said divalent cations, step (b), to impart apreselected specific density to said slurry, such that the pellets soproduced have different buoyancy characteristics and can either float,sink or float-sink-float.

Thus it is an object of the present invention to provide anambient-temperature-process which is easily adaptable to ensurepreferable size and density of the feed, does not involve thedisadvantageous processing with high temperatures and pressures ofpresently available commercial feed and does not require the use ofexpensive processing equipment. A further object of the invention is toprovide the ambient-temperature-processed feed that is free of hightemperature and pressure processing, water-stable and maintains propernutrient and ingredient levels, thereby reducing the necessity ofoverfortification. Said ambient-temperature-processed feed could also bea useful means of administering heat-labile drugs and vaccines toaquatic animals. A further object of the invention is that theambient-temperature-processed feed can be provided as preformulated andprocessed feed or as a dry-mix for easy, low cost on-site production.

DETAILED DESCRIPTION OF THE INVENTION

An ambient-temperature process for making aquatic animal feed and theambient-temperature-processed feed so produced are provided according tothe present invention, comprising (a) mixing alginate, feed ingredientsand fresh water to make a slurry wherein said slurry comprises 0.5-10%alginate, and (b) exposing said slurry to divalent cations to form awater stable alginate gel, and (c) forming a water stable aquatic feedpellet.

The phrases "ambient-temperature-process" or"ambient-temperature-processed,, as used herein and in the claims meanthe process carried out at low temperatures; that is between about 3° C.to 156° C. Freezing weakens the alginate slurry and extremely hightemperatures degrade any heat labile ingredients.

The phrase "aquatic animal" as used herein and in the claims means anymarine or fresh water organism, such as but not limited to: Haliotissp., Salmo sp., Menidia sp., Plecoglossus sp., Hypophthalmichthys sp.,Mylio sp., Oreochromis sp., Lepomis sp., Salvelinus sp., Schilbeadessp., Ictalurus sp., Oncorhynchus sp., Gadus sp., Cyprinus sp.,Epinephelus sp., Archoplites sp., Sparus sp., Carassius sp.,Ctenopharyngodon sp., Mugil sp., Poecilia sp., Melanogrammus sp.,Merluccius sp., Clupea sp., Heteropneustes sp., Catla sp., Labeo sp.,Scarus sp., Anguilla sp., Micropterus sp., Chanos sp., Misgurnus sp.,Esox sp., Hippoglossoides sp., Xiphophorus sp., Pollachius sp.,Sphoeroides sp., Pagellus sp., Rutilus sp., Anoplopoma sp., Morone sp.,Raja sp., Katsuwonus sp., Channa sp., Longirostris sp., Acipenser sp.,Xiphophorus sp., Scophthalmus sp., Coregonus sp., Pseudopleuronectessp., Seriola sp., and Tilapia sp. Preferred aquatic animals are FOODFISH: channel catfish, carp species, milk fish, tilapia, salmon species,trout species, and red fish; SPORT FISH: largemouth bass, bluegill,northern pike, walleye, yellow perch, small mouth bass, fathead minnow,shiners, shad species, trout species, and salmon species, andINVERTEBRATES: crab, crayfish, and shrimp species; and non-food fishused as pets in aquariums.

The term "alginate" as used herein and in the claims means apolysaccharide or polymannuronate and is intended to includehydrophilic, or water-loving derivatives of alginic acid, such as butnot limited to alginic acid, sodium alginate, potassium, ammonium, orpropylene glycol alginates, KELMAR, KELCO-GEL, KELTOSE, KELCOSOL, ALTO,ALMAN, ALLOID, ALLOSE, KELGIN, MINUS, and PROTANAL. Alginic acid is anatural colloidal polyuronic acid extracted from several types ofseaweed, composed mainly of anhydrous β-D mannuronic acid residueslinked together in the 1:4 position to form a long straight chainmolecule. Without intending to limit the invention, and by theory only,it is thought that algin is changed by a reaction with calcium or otherdivalent cation from a water soluble algin to a water insoluble alginategel. This gelling reaction occurs at low-temperatures allowing for theproduction of an ambient-temperature-processed feed. The firmness of thefinal feed pellet can be adjusted by the concentration of algin added tomake the slurry. Generally a higher percentage of algin results in afirmer pellet. Preferred is the ambient-temperature-process orambient-temperature-processed feed wherein said slurry comprises 1.5%-3%alginate.

The phrase "feed ingredients" as used herein and in the claims means anyanimal or vegetable material suitable to meet the nutritional needs ofaquatic animals, such as a particular species' total proteinrequirements. Preferred feed ingredients are those selected to meet theleast cost formulation practices of typical feed producers. The percentfeed ingredients that can be added is dependent on the type of algin,feed ingredient, size of feed ingredient particle, and the concentrationof algin in solution. In general, feed ingredients can be present in aquantity between about 0-90 weight percent. Preferably, feed ingredientscomprise about 20-60 weight percent. Also preferred are feed ingredientsthat have been ground to a small particle size, such as a fine powder of0.5-2 mm.

The phrase "animal material" means any portion of the body or remains ofany animal, land or aquatic, suitable for aquatic animal feed. Suchanimal material may include, but is not limited to fats, tallow or oils,meat scrap, fish meat or meal, animal organs and glandular meal, poultryby-products meal, fish solubles, crab, shrimp or other crustacean meal,blood products, milk products, blood meal, meat and bone meal, poultryfeather meal, casein, and other dried products as described in theOfficial Publication of the Association of American Feed ControlOfficials, which is hereby incorporated by reference in its entirety. By"fish meal" as used herein and in the claims, it is intended to includeany feed product formed by the processing or raw marine materials, presscakes, press water, crab meal, shrimp meal, etc., and aqueous extract ofmarine materials.

The phrase "vegetable material" as used herein and in the claims meansany proportion or component of a plant from unicellular or multicellularmembers of the plant kingdom. Such vegetable material may include, butis not limited to flour, meal, bran, grains, polishings, middlings, orsolubles produced from any seeds, such as of rice, wheat, oats, millet,corn, rye, barley, peanuts, peas, kidney, lima, lentil, cotton,sunflower and soy beans; legumes or leafy plants, such as vetch,alfalfa, clover, spinach, and pea pods; stalk vegetables, such as corn,tomatoes, and green peppers; or root vegetables, such as carrots,turnips, beets, onions, and potatoes; molasses, brewer's grains, canolameal and other vegetable materials similarly defined by the Feed ControlAssociation.

The phrase "least cost formulation" as used herein and in the claimsrefers to the practice of using feed ingredients that are the leastexpensive and currently available at the time of formulation but whichwill meet the protein content requirements of the total formulation. Thepresent invention is compatible with least cost formulation practices,so that it is possible to use any conventional feed ingredient toachieve a specific nutritional goal in the fish feed so long as thetotal formulation meets the requirements of the present invention.

The phrase "fresh water" as used herein and in the claims refers topotable treated or untreated (well or spring) water, water fromnon-marine sources such as rivers, streams, lakes, well, municipal waterthat contains less than 0.5 parts per thousand salt.

The order of components listed in said mixing step (a) is not meant tobe limiting. The present invention is intended to include mixing ofcomponents of step (a) in any order. For instance, alginate can behydrated in fresh water to form a slurry to which fortifying agentsand/or feed ingredients, either dry or pre-mixed with fresh water, canbe added. Feed ingredients and fortifying agents can be mixed with freshwater, to which alginate can be added. Further, feed ingredients,fortifying agents and alginate can be pre-mixed as dry ingredients andthen mixed with fresh water. Any other combination or permutation ofaddition sequences to form the slurry of step (a) are intended in thisinvention.

The term "exposing" as used herein and in the claims refers to any meansof introducing a divalent cation solution to a slurry, the order ofintroduction is not meant to be limiting. Such introduction means mayinclude, but is not limited to spraying, dropping, stirring, mixing,etc. For instance, said slurry can be sprayed into said divalent cationsolution, such as a calcium bath. Conversely, said divalent cationsolution can be introduced into said slurry. Without intending to belimiting, and by theory only, it is believed that when the feed slurrycontacts the calcium bath, a reaction takes place that forms an ionicbond between the algin and the calcium. This causes a conformationalchange in the algin molecule pulling the hydrophilic group of the alginpolymer into the calcium ion. This reaction forces the hydrophobicgroups of alginate out and makes the gel insoluble in water, thus waterstable.

The phrase "divalent cations" as used herein and in the claims includesberyllium, magnesium, calcium, strontium, iron, chromium, nickel,copper, zinc, potassium. The amount of divalent cations in the finalpreparation can be trace amounts or up to the solubility of the salt inwater. Preferred is the ambient-temperature-process or feed so producedwherein said slurry is exposed to a solution comprising divalentcations. The phrase "solution comprising divalent cations" as usedherein and in the claims refers to any liquid of fresh or sea waterhaving divalent cations.

Most preferred are the above-mentioned ambient-temperature process andfeed so produced wherein said divalent cation is calcium and is providedeither in a solution comprising about 3% divalent cations or in seawater.

The phrase "marine water" or "sea water" as used herein and in theclaims refers to water found in the basins of the world's seas, oceans,bays, estuaries and/or water that contains more than 3 parts perthousand salinity.

The amount of total water (fresh and/or sea water) in saidambient-temperature-processed feed of the present invention can bepresent in a quantity of between about 30 to 98 weight percent.

The phrase "water stable" as used herein and in the claims refers to afeed which is coherent and does not readily disintegrate in water for atleast 7 days in laboratory conditions of 2 days in typical warm waterpond aquaculture conditions.

The pellets of the invention can be formed by any conventional meansknown to one of ordinary skill in the art, such as slicing, chopping,spraying or low-pressure extruding at ambient-temperatures. Said formingstep does not require the use of expensive processing equipment, such asa high pressure steam extruders, including Anderson or Whingerextruders, or high pressure friction type extruders including InstaProextruders. At high enough divalent cation concentrations, pellets willform spontaneously when the feed slurry contacts the divalent cation.

Preferably, the present invention provides the above-mentionedambient-temperature process wherein said slurry further comprises one ormore fortifying agents including vitamins, minerals, pigmentation aids,proteins, natural or synthetic amino acids (natural or synthetic), fats,oils, flavorings, medicaments, antioxidants and foam stabilizers.Fortifying agents can be present in a quantity between about 0-88 weightpercent of the total feed.

The phrase "fortifying agents" as used herein and in the claims meansthose nutrition supplementing and balancing agents, or those ingredientswhich add desirable texture, or those ingredients necessary to aid ormaintain proper health of the animal or any other agent suitable foraquatic animal feed. Such fortifying agents include but are not limitedto vitamins, minerals (such as phosphorous, selenium, iodine, zinc,copper, etc.), proteins, amino acids, fats, oils, flavorings,carotinoids and other pigmentation aids, medicaments (such asantibiotics, growth promoters or vaccines), and foam stabilizers (suchas xanthine gum, soap, BENEFIBER, protein, casein, malted milk, milkproteins, albumin, ionic and non-ionic soaps, gelatin, food gums, andguar gum). Preferred amino acids are arginine, histidine, isoleucine,leucine, valine, lysine, phenylalanine, methionine, threonine andtryptophan.

More preferably, the present invention provides the above-mentionedambient-temperature process further comprising the step of whipping acontrolled amount of air or nitrogen into said slurry produced by step(a) before exposing said slurry to divalent cations step (b) to impart apreselected specific density to said pellet.

The term "whipping" as used herein and in the claims refers to theordinary and customary definition and using any means to introduce airor a gas, such a oxygen or nitrogen, into the feed slurry to impart aparticular specific density. The term is intended to include but is notlimited to mixing, agitating, etc. The specific density of the feed canbe adjusted, depending on the amount of air or gas whipped into theslurry, so that the feed has a buoyancy to enable it to float on thesurface of the water, or may sink to the bottom of the tank, pond orpool. Also, the feed may be processed so that it has the ability tofloat-sink-float.

By theory only and not meant to be limiting, it is thought that whenformulated at the correct density the feed will float-sink-float by thefollowing mechanism. When the feed is first exposed to the divalent ionthe reaction with the algin has not taken place through the entire feedparticle. As the reaction takes place, the molecules of thepolysaccharide are pulled closer together. Once the feed particles arepulled tight they squeeze out water from the pellet. This loss of waterout of the pellet will increase the density of the pellet, making thefeed sink. On the bottom the feed pellet will slowly rehydrate, thusdecreasing the density and the pellet will refloat to the surface. Theduration of each of the float-sink-float phase is dependent on theamount of: feed ingredients, algin, and air in feed.

Preferred is the ambient-temperature-processed feed that has a buoyancyto enable it to float, that is the pellet has a specific density of lassthan 1 g/cm³.

It is contemplated that a dry mix of feed ingredients, fortifyingingredients and alginate are provided to farmers, whereby a machinecould draw fresh water from any source available, mix the dryingredients into a slurry, then expose, such as but not limited tospray, drop or deposit, said slurry into a pond or seawater containingdivalent cations thus forming a pellet.

The invention can be further illustrated by the following non-limitativeexamples. The components and specific ingredients are presented as beingtypical, and various modifications can be derived in view of theforegoing disclosure within the scope of the invention.

    ______________________________________                                        FEED INGREDIENT       PERCENT                                                 ______________________________________                                        EXAMPLE 1. COMPLETE FEED                                                      FISH MEAL             35                                                      CORN MEAL             30                                                      ALGIN                  2                                                      COD LIVER OIL          2                                                      VITAMIN PREMIX         1                                                      WATER                 30                                                      EXAMPLE 2. COMPLETE FEED                                                      POULTRY BY PRODUCT MEAL                                                                             35                                                      CORN MEAL             30                                                      ALGIN                  2                                                      COD LIVER OIL          2                                                      VITAMIN PREMIX         1                                                      WATER                 30                                                      EXAMPLE 3. HIGH PROTEIN FEED                                                  FISH MEAL             75                                                      WATER                 23                                                      ALGIN                  2                                                      EXAMPLE 4. LOW PROTEIN FEED                                                   Corn Meal             75                                                      WATER                 23                                                      ALGIN                  2                                                      EXAMPLE 5. HIGH LIPID FEED                                                    Cod liver oil         75                                                      WATER                 23                                                      ALGIN                  2                                                      EXAMPLE 6. PALATABLE FEED                                                     Fresh Cow liver       80                                                      WATER                 21                                                      ALGIN                  2                                                      ______________________________________                                    

The foregoing disclosure includes all the information deemed essentialto enable those skilled in the art to practice the claimed invention.Various modifications of the invention in addition to those shown anddescribed herein will be apparent to those skilled in the art from theforegoing description. Such modifications are also intended to fallwithin the scope of the appended claims.

What is claimed is:
 1. An ambient-temperature process for making a waterstable aquatic animal feed comprising:(a) mixing alginate, feedingredients consisting essentially of one or more of vitamins, minerals,pigmentation aids, proteins, amino acids, fats, oils, flavorings,medicaments, and foam stabilizers and fresh water in ambienttemperatures to make a slurry containing 0.5-10% alginate, (b) exposingsaid slurry to calcium in ambient temperatures to form a water stablealginate gel that holds said feed ingredients together, wherein saidslurry contains 1.5-3% alginate, and (c) forming said slurry intopellets in ambient temperatures.
 2. The ambient-temperature process ofclaim 1, further comprising the step of whipping a controlled amount ofair or nitrogen into said slurry before exposing said slurry to saidcalcium to impart a preselected specific density to said pellet toenable said pellet to float.
 3. The ambient-temperature process of claim1, wherein said calcium is in solution, which contains about 3% calcium.4. The ambient-temperature process of claim 1, wherein said calcium isin is sea water.
 5. The ambient-temperature process of claim 1, whereinsaid alginate and said feed ingredients are first dry-mixed, then saiddry-mix is mixed with said fresh water to form said slurry.
 6. Theambient-temperature process of claim 1, wherein said alginate and freshwater are mixed to form a solution, then said solution is mixed withsaid feed ingredients to form said slurry.
 7. The ambient-temperatureprocess of claim 1, wherein said medicaments consists essentially ofantibiotics, growth promoters or vaccines.